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Introduction : Rubber is a naturally occurring polymer, and a very good one, when added to concrete it will increase its elasticity, decrease its brittle point and increase its softening point. In General, the purpose of addition of the rubberized materials to concrete is to improve its properties and to study its effect on workability.

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Objectives: The objective of this study is to show the effect of adding rubber to concrete to improve the properties of concrete. and the effect of adding rubber as an admixture on the workability, strength of concrete, water absorption and thermal insulation. The benefits of the addition of rubber too, to minimize the risk of pollution, and to study the deformation properties of Portland cement concrete with rubber waste additive.

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Concrete and Rubber Concrete mixtures with and without rubber wastes with the same compressive strength were prepared in this work. The rubber additive were used as coarse aggregate replacement in concrete mixtures. The percent of coarse aggregate by volume is to be replace by rubber is (0%, 25%, 50%, 75% and 100% ).

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Cement and fine aggregate were batched by weight while water batched by volume. W\C = O.55 The fresh mortar mixtures were prepared using proportions of (1: 2 : 3 ) by weight for cement, sand, and aggregate respectively for all mixtures used in this study. Many of cubes will be molded for compressive strength. Curing ages of 3, 7,and 28 days for all mixtures were applied.

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Flat slab specimens are made with and without rubber to show the effect of adding rubber on thermal conductivity. SLAB(20*20*4 cm) Hollow concrete block with holes are made with and without rubber.BLOCK (40*20*20 cm).

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Experimental tests results Compressive Strength and slump Compressive strength specimens were prepared by casting the fresh mortar in two layers in steel cubes molds with dimensions of 100 by 100 by 100 mm. Each layer was compacted 16 strokes according ASTM C After 24 hour the cubes specimens were remolded and cured in water for 3, 7 and 28 days.

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After curing process, mortar cubes were tested by compressive strength machine as shown in the figure below to measure the compressive load and compressive strength at which cubes will fail.

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Tables are summarizes concrete compressive strength and slump tests results for type of concrete B200 with and without rubber MIX ONE – CUBES (100*100*100 ) 0.0% aggregate by weight is to be replaced by shredded tires. Specimens Slump (mm) Compressive Strength at 28 days (KN) A1\ A1\ A1\325200